Simplify the Expression: 71a+12b-(25ab+4a) Using Like Terms

The negative sign outside the parentheses acts like multiplying by -1. Just like $-1 \times (25ab+4a) = -25ab-4a$, you must apply it to every term inside.

Like terms have the same variables with the same powers. Here, $71a$ and $4a$ are like terms, but $12b$ and $25ab$ are different.

No! The term $12b$ has only variable b, while $25ab$ has both variables a and b. They're not like terms, so they stay separate.

Check that each term inside the parentheses gets the negative sign. $-(25ab+4a)$ should become $-25ab-4a$, not $-25ab+4a$.

Look for like terms and combine them. Here, combine $71a-4a=67a$, then write all terms together: $67a+12b-25ab$.